PNNL

Abstract

Recently, long-fiber injection molded thermoplastics (LFTs) have generated great interest within the automotive industry as these materials can be used for structural applications in order to reduce vehicle weight. However, injection-molding of these materials poses a great challenge because of two main reasons: (i) no process models for LFTs have been developed that can be used to predict the processing of an LFT part, and (ii) no experimental characterization methods exist to fully characterize the as-formed LFT microstructure to determine the fiber orientation and length distributions and fiber dispersion that are critical for any process model development. This report summarizes the work conducted during the fiscal year 2006 (FY06) that includes (i) the assessment of current process modeling approaches, (ii) experimental evaluation of LFT microstructure and mechanical properties, and (iii) the computation of thermoelastic properties using the measured and predicted orientation distributions as well as the measured fiber length distribution. Our objective is two-fold. First, it is necessary to assess current process models and characterization techniques in order to determine their capabilities and limitations, and the necessary developments for LFTs. Second, before modeling the nonlinear behaviors of LFTs, it is essential to develop computation tools for predicting the elastic and thermoelastic properties of these materials.